1. Field of the Invention
The present invention relates to a spray device for an endoscope which is inserted into a treatment tool insertion channel of the endoscope to spray a liquid in a body cavity and the like.
2. Description of the Related Art
FIG. 1 shows the distal end of a conventional spray device. The spray device can be inserted into and pulled out of a treatment tool insertion channel of an endoscope (not shown). The conventional spray device is provided with a flexible liquid transfer tube 91 which is made of an elastic material, and a spray nozzle 99 which is connected to the distal end of the liquid transfer tube 91. The spray nozzle 99 is provided, in front of the opening of the distal end of the liquid transfer tube 91, with a spiral member 92. The spiral member 92 is provided on an outer peripheral surface thereof with a spiral groove 93. The spray nozzle 99 is further provided with an end cap 94. The end cap 94 is provided at the front end thereof with an orifice 96 and is snugly fitted onto a tubular nozzle body 98 and covers the spiral member 92 in a manner so as to close the entire peripheral opening of the spiral groove 93, so that the spiral groove 93 functions as a liquid guide channel through which liquid runs from the liquid transfer tube 91 to the orifice 96. The rear end (the right end as viewed on FIG. 1) of the end cap 94 is fixedly fitted on the front end of the tubular nozzle body 98 of the spray nozzle 99, while the distal end of the liquid transfer tube 91 (with respect to the user) is fixedly fitted on the rear end of the nozzle body 98. The spray nozzle 99 is provided, in the end cap 94 between an inner end surface 97 of the end cap 94 and a front end surface (left end surface as viewed in FIG. 1) of the spiral member 92, with a liquid whirling chamber 95. An inlet and an outlet of the spiral groove (spiral channel) 93 are provided the front end of the nozzle body 98 and the liquid whirling chamber 95, respectively. The liquid whirling chamber 95 is shaped so that the liquid which spurts from the outlet of the spiral groove 93 whirls about the axis of the spray nozzle 99 (i.e., the axis of the liquid transfer tube 91) in the liquid whirling chamber 95. The axial center of the orifice 96 is coincident with that of the liquid whirling chamber 95. The inner end surface 97 of the end cap 94, which defines the front inner surface of the liquid whirling chamber 95, is formed as a circular conical surface which tapers inwards from the front end surface of the spiral member 92 to the orifice 96 (i.e., from right to left as viewed in FIG. 1).
Due to such a structure of a conventional spray device, the liquid (e.g., a medicinal liquid or a coloring liquid) which is transmitted via the liquid transfer tube 91 from the proximal end thereof spurts from the orifice 96 as a spray, having a certain spray angle, via the spiral groove 93 and the liquid whirling chamber 95 while whirling in the liquid whirling chamber 95.
The spray distribution becomes wider as the direction of the flow of the liquid spurting from the orifice 96 is closer to a circumferential direction about the axis of the spray nozzle 99. The liquid which whirls within the liquid whirling chamber 95 runs to the orifice 96 while gradually changing the direction of the flow due to the reaction force that the liquid receives from the inner end surface 97 when the liquid whirls along the inner end surface 97. FIG. 2 shows the direction of the flow of the liquid which whirls within the liquid whirling chamber 95 along the inner end surface 97 thereof in the conventional spray device. The closer the flow is to the orifice 96, the greater the angle of the direction of the flow with respect to a circumferential direction about the axis of the spray nozzle 99 (the axis of the orifice 96) becomes, since the inner end surface 97 is formed as a circular conical surface. In the particular case shown in FIG. 2, the following condition is satisfied:
xcex81 less than xcex82 less than xcex83 less than xcex84.
Accordingly, with such a conventional spray device, it is difficult to spray the liquid on, for example, a target inner part of the body, with a sufficient spray distribution.
It is an object of the present invention to provide a spray device for an endoscope which can spray a liquid on, for example, a target inner part of the body, with a sufficient spray distribution.
To achieve the object mentioned above, according to the present invention, a spray device used for an endoscope is provided, the spray device having a liquid transfer tube and a spray nozzle connected to a distal end of the liquid transfer tube, the spray nozzle including at least one spiral guide channel positioned in front of the distal end of the liquid transfer tube; a liquid whirling chamber positioned in front of the at least one spiral guide channel to be connected to an outlet thereof; and an orifice formed at a center of a front inner surface of the liquid whirling chamber. The front inner surface includes a concave surface, and the front inner surface is formed so that the orientation of a tangential plane lying on a point on the front inner surface becomes closer to the orientation of a plane normal to the axis of the spray nozzle as the point on the front inner surface approaches the axis of the spray nozzle.
In an embodiment, the concave surface is formed as a spherical surface.
In another embodiment, the concave surface is formed as a series of at least two circular conical surfaces which have different diameters and different taper angles with respect to the axis of the spray nozzle.
Preferably, the spray nozzle further includes a spiral member on which at least one spiral groove is formed; and an end cap on which the orifice is formed and which is snugly fitted on the spiral member in a manner so as to close an entire peripheral opening of the at least one spiral groove to define the at least one spiral guide channel.
The liquid whirling chamber is defined between the end cap and the spiral member, wherein an inner end surface of the end cap defines the front inner surface of the liquid whirling chamber 20.
Preferably, the liquid whirling chamber is shaped so that a liquid which spurts from an outlet of the at least one spiral guide channel whirls about the axis of the spray nozzle in the liquid whirling chamber, an axial center of the orifice being coincident with that of the liquid whirling chamber.
According to another aspect of the present invention, a spray nozzle is provided, which is to be fixed to a distal end of a liquid transfer tube that is inserted into and pulled out of a treatment tool insertion channel of an endoscope, the spray nozzle including at least one spiral guide channel positioned in front of the distal end of the liquid transfer tube so that an inlet of the at least one spiral guide channel is connected to the distal end of the liquid transfer tube; a liquid whirling chamber positioned in front of the at least one spiral guide channel to be connected to an outlet thereof; and an orifice provided at a center of a front inner surface of the liquid whirling chamber. The front inner surface includes a concave surface; and the concave surface is formed so that the orientation of a tangential plane lying on a point on the front inner surface changes as the point of the tangential plane on the front inner surface approaches the axis of the spray nozzle.
In an embodiment, the front inner surface is formed as a spherical surface.
In another embodiment, the front inner surface is formed as a series of at least two circular conical surfaces which have different diameters and different taper angles with respect to the axis of the spray nozzle.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 11-324934 (filed on Nov. 16, 1999) which is expressly incorporated herein by reference in its entirety.